Geezer electronics or a short history lesson...

This may or may not be interesting to some or all. I was cleaning out some old storage areas in my garage, and came across an item that really bridges a wide expanse of computing as we know it. The ‘geezer’ is me. Well before subsecond response times, nanoelectronics, the ‘chip’, certainly microprocessors, LED’s, and the like were some pretty crude looking parts. The picture you are looking at, I took with my ‘digital’ camera (no longer film) this afternoon out on the picnic bench. You need to be logged in to see the picture.

You are looking at ‘core memory’. The black toroidal cores in the picture are 1 (one) bit each. You could put several hundred of these in a tablespoon. 8 bits to a byte. You should see 10X10 matrices. The copper colored wires are the address lines X and Y, and you should notice a second copper wire running in parallel with one of the address lines. The second copper wire is the ‘Read line’. Notice next the green line, that’s the inhibit line. This memory ran at about 60 volts. Each time the memory was addressed, the ferrite core would want to flip to the opposite state. If it was a 0 it would switch to a 1, unless an “inhibit line” was active at the same time that the addressing and read lines were. This would cancel out the magnetic field generated, and leave it’s state as it was.

That’s the ‘so what’ part. The interesting part of this technology was that this type of memory lasted until the bipolar transistor replaced it. Even more interesting is that these core storage units were actually a cottage industry. These were built by women in upstate New York. Those wires are actually hand sewn. Yep! A 64KiloByte storage unit cost about $100,000 to be built and tested. So when we think about ‘concise’ programming techniques, major applications in geezer times were of course single threaded applications (like our Arduino’s) and very memory constrained. Just thought I’d share this with the group.

Core.jpg

Cool. Interestingly, you're not the only one with such a classical relic on your hands. Several are for sale on ebay. I'm kind of surprised. http://www.ebay.com/bhp/core-memory

this type of memory lasted until the bipolar transistor replaced it.

longer than that. Transistor memory takes about 6 transistors per cell, so a core memory cell was significantly smaller than transistor memory until after the widespread availability of integrated circuits (and specifically, the Intel 1103 1k DRAM, IIRC.) http://en.wikipedia.org/wiki/Magnetic-core_memory I was still using a mainframe with actual core memory in the early to mid 1980s.

Interesting post, thanks for sharing

Cottage Industry... until around 1978 when the bottom fell out.

I was working for Digital Equipment when it was announced that our Natick facility was closing down it's magnetic memory division. I got to see parts of the plant just before it all went poof... It was neat to see the core testing robot drop tiny ferrites onto what looked like a sewing needle, pump current through it and toss it left or right (good/bad). Up until someone coveted and absconded with it, I had a nice 18K memory core board hanging on my wall at the office. It made a lovely piece of desk art.

Thanks for sharing.

westfw: I was still using a mainframe with actual core memory in the early to mid 1980s.

Yeah, me too in the early 80's; Honeywell.

afremont:

westfw: I was still using a mainframe with actual core memory in the early to mid 1980s.

Yeah, me too in the early 80's; Honeywell.

Cut my teeth on the Series 6000, DPS-8, etc., with the GCOS O/S. Took care of the FEP software for a while, NPS mostly. Did some custom stuff and extensions. Getting dissimilar machines to communicate was quite a challenge back then. Come to think of it, getting similar machines to talk wasn't much easier.

westfw:

this type of memory lasted until the bipolar transistor replaced it.

longer than that. Transistor memory takes about 6 transistors per cell, so a core memory cell was significantly smaller than transistor memory until after the widespread availability of integrated circuits (and specifically, the Intel 1103 1k DRAM, IIRC.) http://en.wikipedia.org/wiki/Magnetic-core_memory
I was still using a mainframe with actual core memory in the early to mid 1980s.

Sounds like you were using some downlevel equipment. Bipolar memory was in full bloom in the very early 70’s. IBM’s 370 was using bi-polar memory from the day it was available. SYS370/3145 (1971) was the at the leading edge of it. It was also able to emulate every ‘system’ known at that time through the innovative microprogramming.

What? None of you guys programmed it flipping bits with a magnet? I'm so disappointed....

:P

[quote author=Jack Christensen link=topic=166819.msg1243548#msg1243548 date=1368809044]

afremont:

westfw: I was still using a mainframe with actual core memory in the early to mid 1980s.

Yeah, me too in the early 80's; Honeywell.

Cut my teeth on the Series 6000, DPS-8, etc., with the GCOS O/S. Took care of the FEP software for a while, NPS mostly. Did some custom stuff and extensions. Getting dissimilar machines to communicate was quite a challenge back then. Come to think of it, getting similar machines to talk wasn't much easier. [/quote]

I wrote COBOL and GMAP for a few years then switched to all assembler and systems programming. I wrote some kind of cheesy comm adapter to get SNA and CICS to talk to each other if I recall correctly, it involved a Level 6 but my code ran on the mainframe. Wrote tons of GMAP for a software company you probably know of since there weren't that many third party systems software vendors for Honeywell. We did a Tape Management System, a file utility package and a production job scheduler amongst some other things. I wrote some filsys modifications to add some features to MME GEFSYE that GE left out. Fun stuff, I really miss GCOS.

afremont: I wrote COBOL and GMAP for a few years then switched to all assembler and systems programming. I wrote some kind of cheesy comm adapter to get SNA and CICS to talk to each other if I recall correctly, it involved a Level 6 but my code ran on the mainframe. Wrote tons of GMAP for a software company you probably know of since there weren't that many third party systems software vendors for Honeywell. We did a Tape Management System, a file utility package and a production job scheduler amongst some other things. I wrote some filsys modifications to add some features to MME GEFSYE that GE left out. Fun stuff, I really miss GCOS.

I debugged COBOL for the applications guys but never wrote any ;) Enjoyed GMAP, wrote a lot of that. My undergrad thesis was basically improvement/mods to filsys saves and restores. GCOS = God's Chosen Operating System ;)

Magnetic memories are back - see http://www.everspin.com/ :)

I was still using a mainframe with actual core memory in the early to mid 1980s.

Sounds like you were using some downlevel equipment. Bipolar memory was in full bloom in the very early 70's.

It was a DECSystem KL-10, which was introduced in 1974, originally with core memory. The particular system I'm thinking of (Sushi.stanford.edu) was acquired well after DEC announced the discontinuation of the PDP10s, and it's quite possible that the core memory unit (which was a 3rd party external box, rather than internal memory) was a "bargain" because of it's "obsolete" status. It was an "interesting" time where PDP10 lovers could pick up hardware for prices comparable to the transportation costs plus the first year power bill...

Ahh yes! The old third party memory trick. There were many 'strap-on' memory boxes that came in many flavors for system integrators. Those memories and memory busses were (if I can recall correctly) running around 1.5 - 3 usec read/write times. I watched many times as dozens of the integrators brought in 1024 bit DRAM chips by the wheelbarrel load to repopulate their interface boxes after an 'Engineering Change'. One outfit had the nickname 'Mission Impossible', religiously every Monday they brought in their MI team to spend the week trying to get a Spectra70 to read a punched card.

MisterResistor: Just thought I'd share this with the group.

In the early 1960s I went on a school trip to Ferranti in London to see [u]a[/u] computer. It had a similar, though more crude, core memory. Just one array about 12 * 12 and, if I remember correctly, there were only 3 wires on each ring. x and y directions and a third wire going diagonally to each ring. The wires were threaded through each ring a couple of times, not just passing through. I've since learned that it was using 6 bit 'bytes'.

Very good! I'd venture to say it had a "fourth wire" though a core. Always had to have a specific "read" line and the "inhibit" line to prevent a 'bit flipping' when the core was accessed. I think your 6 bit byte was used as an 'octal' value. (Went the way of the 5 bit Baudot and the Dodo bird ;)) It is still amazing how far we've come from that technology.

Seeing your referrence to Baudot reminded me that the place was FULL of reels of punched paper tape!

It is still amazing how far we've come from that technology.

Yes indeed. The 'hard drive' on that machine was a horizontal drum, about 4" in diameter, with the (about 10) heads 'resting' on top. It was all open and I could see the drum revolving and the heads moving. It was like a phonograph compared to todays hard drives. And it probably cost much more to make than my current 2Tb hard drive cost me.

MisterResistor: Very good! I'd venture to say it had a "fourth wire" though a core. Always had to have a specific "read" line and the "inhibit" line to prevent a 'bit flipping' when the core was accessed. I think your 6 bit byte was used as an 'octal' value. (Went the way of the 5 bit Baudot and the Dodo bird ;)) It is still amazing how far we've come from that technology.

One of the computers I programmed in college (1975 - 1979) had 6-bit characters (CDC 6600).

On my second digital camera that I bought in 2002, I put in a 128 megabyte smartmedia memory card that had the same capacity as the disk space for the 5 person team I worked with at my first computer job (Data General) in 1979. The disk in 1979 3-4' high CDC removable media with multiple platters that were the same size as most washing machines, and a smartmedia card is 45mm x 37mm. Checking at newegg.com, I can buy a 32GB class 10/UHS card for under $25. I recall when I first bought the 128MB SM card it was in the $50 range (maybe $75, I don't remember). Lets see, the new SD-HC card has 256 times the capacity, 10 times the speed, and 1/2 the cost of the SM card. I imagine the specs against the disk I used in 1979 would be much greater, particularly in cost.

The annoying Australian has some fun videos about old hardware:

eg. https://www.youtube.com/watch?v=CBjoWMA5d84